The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total ...The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature (excluding 800 ℃). The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature. The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5 zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking.展开更多
SiO2-supported Ni-Mo bimetallic phosphides were prepared by temperature-programmed reduction (TPR) method from the phosphate precur- sors calcined at different temperatures. Their properties were characterized by me...SiO2-supported Ni-Mo bimetallic phosphides were prepared by temperature-programmed reduction (TPR) method from the phosphate precur- sors calcined at different temperatures. Their properties were characterized by means of ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), H2 temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM), CO chemisorption, H2 and NH3 temperature-programmed desorptions (H2-TPD and NH3-TPD). Their catalytic performances for the deoxygena- tion of methyl laurate were tested in a fixed-bed reactor. When the precursors were calcined at 400 and 500 ℃, respectively, NiMoP2 phase could be formed apart from Ni2P and MoP phases in the prepared C400 and C500 catalysts. However, when the precursors were calcined at 600, 700 and 800 ℃, respectively, only Ni2P and MoP phases could be detected in the prepared C600, C700 and C800 catalysts. Also, in C400, C500 and C600 catalysts, Mo atoms were found to be entered in the lattice of Ni2P phase, but the entering extent became less with the increase of calcination temperature. As the calcination temperature of the precursor increased, the interaction between Ni and Mo in the prepared catalysts decreased, and the phosphide crystallite size tended to increase, subsequently leading to the decrease in the surface metal site density and the acid amount. C600 catalyst showed the highest activity among the tested ones for the deoxygenation of methyl laurate. As the calcination temperature of the precursor increased, the selectivity to C12 hydrocarbons decreased while the selectivity to C11 hydrocarbons tended to increase. This can be mainly attributed to the decreased Ni-Mo interaction and the increased phosphide particle size. In sum, the structure and performance of Ni-Mo bimetallic phosphide catalyst can be tuned by the calcination temperature of precursor.展开更多
Perovskite-type V-doped titanium-bearing blast furnace slag (VTBBFS) photocatalyst was prepared by high-temperature solid phase method.The influence of calcination temperature on the photocatalytic and antibacterial p...Perovskite-type V-doped titanium-bearing blast furnace slag (VTBBFS) photocatalyst was prepared by high-temperature solid phase method.The influence of calcination temperature on the photocatalytic and antibacterial properties of VTBBFS was studied in details.Its composition and microstructure were evaluated by X-ray diffractometer,ultraviolet-visible absorption spectrometer,Fourier transform infrared spectrometer and scanning electron microscope.The antibacterial properties of VTBBFS to Candida albicans were investigated by flask oscillation method.The results showed that the optical absorption and antibacterial properties of VTBBFS were the best with 10%(ω) doping of vanadium,prepared at 800℃ for 2 h,and its sterilization rate was close to 100% to Candida albicans (ATCC10231).The minimum inhibitory and minimum bactericidal concentrations were 25 and 50 mg/mL.When the concentration was 0.2 μg/mL,the catalyst had the least toxic toxicity.展开更多
A new magnesium phosphate bone cement (MPBC) was prepared as a byproduct of boroncontaining magnesium oxide (B-MgO) after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw ...A new magnesium phosphate bone cement (MPBC) was prepared as a byproduct of boroncontaining magnesium oxide (B-MgO) after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw materials and the effects of calcination temperature on the performance of MPBC. The phase composition and microstructure of the B-MgO raw materials and the hydration products (KMgPO4.6H2O) of MPBC were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that ionic impurities and the levels of toxic elements were sufficiently low in B-MgO raw materials to meet the medical requirements for MgO (Chinese Pharmacopeia, 2O10 Edition) and for hydroxyapatite surgical implants (GB23101.1-2O08). The temperature of B-MgO calcination had a marked influence on the hydration and hardening of MPBC pastes. Increasing calcination temperature prolonged the time required for the MPBC slurry to set, significantly decreased the hydration temperature, and prolonged the time required to reach the highest hydration temperature. However, the compressive strength of hardened MPBC did not increase with higher calcination temperatures. In the 900-1 000 ~C temperature range, the hardened MPBC had a higher compressive strength. Imaging analysis suggested that the setting time and the highest hydration temperature of MPBC pastes were dependent on the size and crystal morphology of the B-MgO materials. The production and microstructure compactness of KMgPOa'6H2O, the main hydration product, determined the compressive strength.展开更多
TiOz nanotubes (TiO2-NTs) were synthesized by the hydrothermal method. Co and Mo active components were supported on a series of the as-prepared TiO2-NTs samples which were calcined at different temperatures. The ef...TiOz nanotubes (TiO2-NTs) were synthesized by the hydrothermal method. Co and Mo active components were supported on a series of the as-prepared TiO2-NTs samples which were calcined at different temperatures. The effects of support calcination temperature of CoMo/TiOz- NTs catalysts on their catalytic performance were investigated for selective hydrodesulfurization (HDS). The samples were characterized by means of the scanning electron microscopy (SEM), the transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy and H2 temperature-programmed reduction (Hz-TPR). The experimental results revealed that TiOz-NTs support calcined under 500℃ can maintain the nanotubular structure with higher surface area and pore volume. Meanwhile, the obtained supported CoMo/TiO2-NTs catalysts exhibited weak metal-support interaction, more octahedral Mo6+ species and high catalytic performance in selective HDS.展开更多
The effect of calcination temperature on the pozzolanic activity of maize straw stem ash(MSSA)was evaluated.The MSSA samples calcined at temperature values of 500,700,and 850℃ were dissolved in portlandite solution f...The effect of calcination temperature on the pozzolanic activity of maize straw stem ash(MSSA)was evaluated.The MSSA samples calcined at temperature values of 500,700,and 850℃ were dissolved in portlandite solution for 6 h,thereby obtaining residual samples.The MSSA and MSSA residual samples were analyzed using Fourier transform infrared spectroscopy,X-ray powder diffraction scanning electron microscopy,and X-ray photoelectron spectroscopy to determine vibration bonds,minerals,microstructures,and Si 2p transformation behavior.The conductivity,pH value,and loss of conductivity with dissolving time of the MSSA-portlandite mixed solution were also determined.The main oxide composition of MSSA was silica and potassium oxide.The dissolution of the Si^(4+) content of MSSA at 500℃ was higher than those of the other calcination temperatures.The conductivity and loss of conductivity of MSSA at 700℃ were higher than those of the other calcination temperatures at a particular dissolving time due to the higher KCl content in MSSA at 700℃.C-S-H was easily identified in MSSA samples using X-ray powder diffraction,and small cubic and nearly spherical particles of C-S-H were found in the MSSA residual samples.In conclusion,the optimum calcination temperature of MSSA having the best pozzolanic activity is 500℃,but excessive agglomeration must be prevented.展开更多
LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)cathode material is prepared by sol-gel method and the effects of Nb^(5+)doping and different calcination temperatures on cathode materials were deeply investigated.Structural and morpho...LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)cathode material is prepared by sol-gel method and the effects of Nb^(5+)doping and different calcination temperatures on cathode materials were deeply investigated.Structural and morphological characterizations revealed that the optimal content of 1 mol%Nb^(5+)can stabilize layered structures,mitigate Ni^(2+)migration to Li layers,improve lithium diffusion capacity,and reduce lattice expansion/shrinkage while cycling.And calcination temperature at 800℃can not only ensure good morphology,but also suppress the mixed discharge of lithium and nickel in the internal structure.Electrochemical performance evaluation revealed that Nb^(5+)doping improves the discharge-specific capacity of the material,which is conducive to ameliorating its rate capability and cycle performance.And the material at 800℃exhibits the highest discharge specific capacity,the best magnification performance,low polarizability,and the best cycle reversibility.展开更多
A series of CeO2-ZrO2-WO3 catalysts for the selective catalytic reduction (SCR) of NO with NH3 were prepared by hydrothermal method. The influence of calcination temperature on the catalytic activity, microstructure...A series of CeO2-ZrO2-WO3 catalysts for the selective catalytic reduction (SCR) of NO with NH3 were prepared by hydrothermal method. The influence of calcination temperature on the catalytic activity, microstructure, surface acidity and redox behavior of CeO2-ZrO2-WO3 catalyst was investigated using various characterization methods. It was found that the CeO2-ZrO2-WO3 catalyst calcined at 600 ℃ showed the best catalytic performance and excellent N2 selectivity, and yielded more than 90% NO conversion in a wide temperature range of 250-500 ℃ with a space velocity (GHSV) of 60000 131. As the calcination temperature was increased from 400 to 600 ℃, the NO conversion obviously increased, but decreased at higher calcination temperature. The results implied that the higher surface area, the strongest synergistic interaction, the superior redox property and the highly dispersed or amorphous WO3 species contributed to the excellent SCR activity of the CeO2-ZrO2-WO3 catalyst calcined at 600℃.展开更多
CuSO4/TiO2 catalysts with high catalytic activity and excellent resistant to SO2 and H2 O,were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH3.The performance of catal...CuSO4/TiO2 catalysts with high catalytic activity and excellent resistant to SO2 and H2 O,were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH3.The performance of catalysts is largely affected by calcination temperature.Here,effects of calcination temperature on physicochemical property and catalytic activity of CuSO4/TiO2 catalysts were investigated in depth.Catalyst samples calcined at different temperatures were prepared first and then physicochemical properties of the catalyst were characterized by N2 adsorption-desorption,X-ray diffraction,thermogravimetric analysis,Raman spectra,Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,temperature-pro grammed desorption of NH3,temperature-programmed reduction of H2 and in situ diffuse reflectance infrared Fourier transform spectroscopy.Results revealed that high calcination temperature had three main effects on the catalyst.First,sintering and anatase transform into rutile with increase of calcination temperature,causing a decrement of specific surface area.Second,decomposition of CuSO4 under higher calcination temperature,resulting in disappears of Br(?)nsted acid sites(S-OH),which had an adverse effect on surface acidity.Third,CuO from the decomposition of CuSO4 changed surface reducibility of the catalyst and favored the process of NH3 oxidation to nitrogen oxides(NOx).Thus,catalytic activity of the catalyst calcined under high temperatures(≥600℃)decreased largely.展开更多
In this study,α-Bi2O_(3)/g-C_(3)N_(4) nanocomposite with direct Z-scheme was successfully prepared through calcination of BiOCOOH/g-C_(3)N_(4) precursor at different temperature.Meanwhile,the effect of calcination te...In this study,α-Bi2O_(3)/g-C_(3)N_(4) nanocomposite with direct Z-scheme was successfully prepared through calcination of BiOCOOH/g-C_(3)N_(4) precursor at different temperature.Meanwhile,the effect of calcination temperature on the physicochemical properties ofα-Bi2O_(3)/g-C_(3)N_(4) was studied.All results confirmed that calcination tempe rature greatly influences structural,morphology,surface states,photoelectrochemical property and photocatalytic(PC)perfo rmance ofα-Bi2O_(3)/g-C_(3)N_(4) composite.Furthermore,theα-Bi2O_(3)/gC_(3)N_(4) composite was applied as photocatalyst to degrade amido black 10 B dye under visible light irradiation.It was found that the composite synthesized at 400℃exhibited the highest PC performance due to the intense visible light absorbance and high separation efficiency of electron and hole pairs.Besides,the possible PC mechanism was proposed that the photo-generated charge carrier migration inα-Bi2O_(3)/g-C_(3)N_(4) photocatalyst followed a Z-scheme structure.Finally,the stability test also manifest that theα-Bi2O_(3)/g-C_(3)N_(4) composite photocatalyst has good stability and reusability,which was a promising candidate for wastewater treatment.展开更多
Activated carbon-supported bimetallic cerium-man- ganese (Ce-Mn/AC) materials were prepared by impregnation method to study the effect of calcination temperature on the structure and adsorption performance of absorb...Activated carbon-supported bimetallic cerium-man- ganese (Ce-Mn/AC) materials were prepared by impregnation method to study the effect of calcination temperature on the structure and adsorption performance of absorbents. The obtained materials were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption-desorption iso- therm, Fourier transformed infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). As the results showed, the diffraction peaks of CeO2 decreased and even disappeared; Mn species were transformed from Mn3O4 to Mn2O3 on the surface of Ce-Mn/AC; the BET specific surface area increased first and then decreased on the elevating calcination temperature; the number of acid functions of AC was reduced after being modified by cerium and manganese All these changes were directly attributed to the synergistic effects between MnOx and CeO2. AC800 exhibited the best phenol adsorption capacity. The adsorption mechanism of phenol on Ce-Mn/AC was discussed with hydrophilic (hydrophobic) interaction and hard and soft acid-base theory.展开更多
Carbon-modified titanium dioxide (TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation (PCO) of gaseo...Carbon-modified titanium dioxide (TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation (PCO) of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400℃ had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range (〈 300℃). However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400℃ contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.展开更多
Lithium-rich manganese-based oxides have the advantages of high discharge specific capacity, so they are potential candidates for advanced lithium battery cathode materials. However, they also have drawbacks to be sol...Lithium-rich manganese-based oxides have the advantages of high discharge specific capacity, so they are potential candidates for advanced lithium battery cathode materials. However, they also have drawbacks to be solved such as serious irreversible loss of capacity and voltage decay in the cycling process. Surface coating method was used in this paper to modify the lithium-rich manganese-based oxide(LRMO,Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)) to improve its electrochemical properties. Zirconium-based compounds coated LRMO materials(ZBC@LRMO) were obtained via the reaction of lithium hydroxide with zirconium n-butanol and subsequent thermal treatment at different temperatures. The results of X-ray diffraction and transmission electron microscopy confirm that the crystal structure and composition of the ZBC coating layer vary with the calcination temperature. The coating layer obtained at 600 ℃ is composed of tetragonal ZrO_(2) and Li_(2)ZrO_(3). The ZBC@LRMO sample with tetragonal ZrO =2 and Li_(2)ZrO_(3) composite exhibits the best electrochemical performance: the discharge capacity of ZBC@LRMO can reach 296 mAh g^(-1) at 0.1 C and 120 mAh g^(-1) at high rate of 5 C.展开更多
In this paper,the effect of high temperature calcination on the structure and properties of bauxite-based homogeneous clinkers calcined at different temperatures for different durations was studied.The results show th...In this paper,the effect of high temperature calcination on the structure and properties of bauxite-based homogeneous clinkers calcined at different temperatures for different durations was studied.The results show that with the rising of calcination temperature and the prolonging of holding time,the volume density of bauxite-based homogeneous clinkers increases and the apparent porosity decreases.After high temperature calcination,the linear expansion of bauxitebased homogeneous clinker is smaller than that of the non-calcined ones.Whether calcined at high temperatures or not,the thermal shock resistance of bauxite-based homogeneous clinkers is good.The crystalline phases of bauxite-based homogeneous clinkers are mainly mullite and corundum.There is more glass phase in the bauxite-based homogeneous clinkers without calcination.After calcination at high temperatures the glass phase content decreases significantly,and the mullite crystals develop better forming the cross-network structure.展开更多
As an industrial solid waste,pyrite cinder exhibited excellent reactivity and cycle stability in chemical looping combustion.Prior to the experiment,oxygen carriers often experienced a high temperature calcination pro...As an industrial solid waste,pyrite cinder exhibited excellent reactivity and cycle stability in chemical looping combustion.Prior to the experiment,oxygen carriers often experienced a high temperature calcination process to stabilize the physico-chemical properties,which presented significant influence on the redox performance of oxygen carriers.However,the effect of calcination temperature on the cyclic reaction performance of pyrite cinder has not been studied in detail.In this work,the effect of calcination temperature on the redox activity and attrition characteristic of pyrite cinder were studied in a fluidizedbed reactor using CH_(4) as fuel.A series of pyrite cinder samples were prepared by controlling the calcination temperature.The redox activity and attrition rate of the obtained pyrite cinder samples were investigated deeply.The results showed that calcination temperature displayed significant impact on the redox performance of pyrite cinder.Considering CH_(4) conversion(80%–85%)and attrition resistance,the pyrite cinder calcined at 1050℃ presented excellent redox properties.In the whole experiment process,the CO_(2) selectivity of the pyrite cinder samples were not affected by the calcination temperature and were still close to 100%.The results can provide reference for optimizing the calcination temperature of pyrite cinder during chemical looping process.展开更多
Precipitation was carried out to obtain manganese carbonate by adding a precipitating agent, sodium carbonate (NaCO<sub>3</sub>). This was followed by calcination of the manganese carbonate (MnCO<sub>...Precipitation was carried out to obtain manganese carbonate by adding a precipitating agent, sodium carbonate (NaCO<sub>3</sub>). This was followed by calcination of the manganese carbonate (MnCO<sub>3</sub>) to obtain manganese dioxide (MnO<sub>2</sub>). For precipitation tests, a pH ranging from 8 to 10, a time of one to two hours, and a temperature of 25°C and 50°C are the parameters that are considered. The calcination of MnCO<sub>3</sub> is carried out under the following conditions: time (1, 2, 3, and 4 hours) and temperature (370°C, 420°C, and 470°C). It should be noted that the temperature range selected for the calcination tests is based on thermodynamic data obtained using the HSC CHEMISTRY software. The results obtained show an effective recovery of manganese at 25°C, in one hour, with a pH of 8.5 with a precipitation yield and manganese content in the precipitate around 98.43% and 24.21%, respectively. During calcination tests, results show an increase in mass loss, for a constant calcination time, as temperature increases. On the other hand, increasing the calcination time at a given temperature causes an increase in mass loss. However, a significant decrease in mass loss is noted at 3 hours of calcination. The highest mass loss is obtained at a temperature of 470°C after 4 hours of calcination.展开更多
We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holdin...We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holding time on crystalline, microstructure and content of aluminum titanate materials to determine the preferred calcining temperature and holding time. XRD and SEM methods were utilized to characterize the crystalline and microstructure of each specimen, Rietveld Quantification software was used for the determination of different crystalline contents of specimens, and Philips plus software was applied to determine the cell parameters of aluminium titanate in different specimens. According to the experimental results, preferred calcining temperature is determined as 1400℃ and preferred holding time is 2 h, at which the grains of aluminum titanate grow completely and the purity of aluminum titanate is 97.2wt%.展开更多
The swung gel fibers were hea, ted to 400 ℃ at 0. .5 ,1, 1.5,2,2.5,3and4 ℃ min^-1 of heating rate, respectivel, and soaked.for 1 h ; then heated to 600 ℃ at 3 ℃ min ^-1 of.heating rate amt soaked for 1 h at last ...The swung gel fibers were hea, ted to 400 ℃ at 0. .5 ,1, 1.5,2,2.5,3and4 ℃ min^-1 of heating rate, respectivel, and soaked.for 1 h ; then heated to 600 ℃ at 3 ℃ min ^-1 of.heating rate amt soaked for 1 h at last calcined m 1 000, 1 100, 1 200, 1 300, and 1 400 ℃.for 1 h, respectively.展开更多
Ternesite(4CaO·2SiO_(2)·CaSO_(4))-Ye’elimite(3CaO·3Al_(2)O_(3)·CaSO_(4))(simplified as TY)cement clinker was successfully prepared from steel slag at 1200℃in this study.XRD,TG/DSC and SEM were us...Ternesite(4CaO·2SiO_(2)·CaSO_(4))-Ye’elimite(3CaO·3Al_(2)O_(3)·CaSO_(4))(simplified as TY)cement clinker was successfully prepared from steel slag at 1200℃in this study.XRD,TG/DSC and SEM were used to analyze the mineral composition and hydration products of the TY clinker.The sintering process and hydration mechanism of the TY clinker were investigated.Results show that a large amount of ternesite and ye’elimite have been formed at 1200℃,while ternesite has not been decomposed.Clinker minerals include ternesite,ye’elimite,gypsum and a small amount of iron phase.Iron phase from steel slag can promote the formation of liquid phase with the presence of gypsum at 1200℃and thus lead to the coexistence of ternesite and ye’elimite.The compressive strength of TY cement cured at 28 d is 59.5 MPa,which is higher than that of P.II 42.5 cement.This research provides a sustainable and energy-effective way for the reutilization of steel slag,an otherwise valueless waste.展开更多
基金The authors would like to thank the financial support from the National Basic Research Program of China fgrant No.2004CB 217806)the National Natural Science Foundation of China (Grant No.20373043) the Scientific Research Key Foundation for the Returned Overseas Chinese Scholars of State Education Ministry.
文摘The acidic modulations of a series of HZSM-5 catalysts were successfully made by calcination at different treatment temperatures, i.e. 500, 600, 650, 700 and 800 ℃, respectively. The results indicated that the total acid amounts, their density and the amount of B-type acid of HZSM-5 catalysts rapidly decreased, while the amounts of L-type acid had almost no change and thus the ratio of L/B was obviously enhanced with the increase of calcination temperature (excluding 800 ℃). The catalytic performances of modified HZSM-5 catalysts for the cracking of n-butane were also investigated. The main properties of these catalysts were characterized by means of XRD, N2 adsorption at low temperature, NH3-TPD, FTIR of pyridine adsorption and BET surface area measurements. The results showed that HZSM-5 zeolite pretreated at 800 ℃ had very low catalytic activity for n-butane cracking. In the calcination temperature range of 500-700 ℃, the total selectivity to olefins, propylene and butene were increased with the increase of calcination temperature, while, the selectivity for arene decreased with the calcination temperature. The HZSM-5 zeolite calcined at 700 ℃ produced light olefins with high yield, at the reaction temperature of 650 ℃ the yields of total olefins and ethylene were 52.8% and 29.4%, respectively. Besides, the more important role is that high calcination temperature treatment improved the duration stability of HZSM-5 zeolites. The effect of calcination temperature on the physico-chemical properties and catalytic performance of HZSM-5 for cracking of n-butane was explored. It was found that the calcination temperature had large effects on the surface area, crystallinity and acid properties of HZSM-5 catalyst, which further affected the catalytic performance for n-butane cracking.
基金supported by the National Natural Science Foundation of China(No.21176177)the Natural Science Foundation of Tianjin(No.12JCYBJC13200)State Key Laboratory of Catalytic Materials and Reaction Engineering(RIPP,SINOPEC)
文摘SiO2-supported Ni-Mo bimetallic phosphides were prepared by temperature-programmed reduction (TPR) method from the phosphate precur- sors calcined at different temperatures. Their properties were characterized by means of ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), H2 temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM), CO chemisorption, H2 and NH3 temperature-programmed desorptions (H2-TPD and NH3-TPD). Their catalytic performances for the deoxygena- tion of methyl laurate were tested in a fixed-bed reactor. When the precursors were calcined at 400 and 500 ℃, respectively, NiMoP2 phase could be formed apart from Ni2P and MoP phases in the prepared C400 and C500 catalysts. However, when the precursors were calcined at 600, 700 and 800 ℃, respectively, only Ni2P and MoP phases could be detected in the prepared C600, C700 and C800 catalysts. Also, in C400, C500 and C600 catalysts, Mo atoms were found to be entered in the lattice of Ni2P phase, but the entering extent became less with the increase of calcination temperature. As the calcination temperature of the precursor increased, the interaction between Ni and Mo in the prepared catalysts decreased, and the phosphide crystallite size tended to increase, subsequently leading to the decrease in the surface metal site density and the acid amount. C600 catalyst showed the highest activity among the tested ones for the deoxygenation of methyl laurate. As the calcination temperature of the precursor increased, the selectivity to C12 hydrocarbons decreased while the selectivity to C11 hydrocarbons tended to increase. This can be mainly attributed to the decreased Ni-Mo interaction and the increased phosphide particle size. In sum, the structure and performance of Ni-Mo bimetallic phosphide catalyst can be tuned by the calcination temperature of precursor.
基金Supported by the National Natural Science Foundation of China (No. 50874029)Important Project of Education Ministry (No.307009)National Basic Research Program (973) (No.2007CB613504)
文摘Perovskite-type V-doped titanium-bearing blast furnace slag (VTBBFS) photocatalyst was prepared by high-temperature solid phase method.The influence of calcination temperature on the photocatalytic and antibacterial properties of VTBBFS was studied in details.Its composition and microstructure were evaluated by X-ray diffractometer,ultraviolet-visible absorption spectrometer,Fourier transform infrared spectrometer and scanning electron microscope.The antibacterial properties of VTBBFS to Candida albicans were investigated by flask oscillation method.The results showed that the optical absorption and antibacterial properties of VTBBFS were the best with 10%(ω) doping of vanadium,prepared at 800℃ for 2 h,and its sterilization rate was close to 100% to Candida albicans (ATCC10231).The minimum inhibitory and minimum bactericidal concentrations were 25 and 50 mg/mL.When the concentration was 0.2 μg/mL,the catalyst had the least toxic toxicity.
基金Funded by the National Natural Science Foundation of China(No.21276264)the Qinghai Province Science and TechnologyDepartment(No.2013-G-208)
文摘A new magnesium phosphate bone cement (MPBC) was prepared as a byproduct of boroncontaining magnesium oxide (B-MgO) after extracting Li2CO3 from salt lakes. We analyzed the elementary composition of the B-MgO raw materials and the effects of calcination temperature on the performance of MPBC. The phase composition and microstructure of the B-MgO raw materials and the hydration products (KMgPO4.6H2O) of MPBC were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that ionic impurities and the levels of toxic elements were sufficiently low in B-MgO raw materials to meet the medical requirements for MgO (Chinese Pharmacopeia, 2O10 Edition) and for hydroxyapatite surgical implants (GB23101.1-2O08). The temperature of B-MgO calcination had a marked influence on the hydration and hardening of MPBC pastes. Increasing calcination temperature prolonged the time required for the MPBC slurry to set, significantly decreased the hydration temperature, and prolonged the time required to reach the highest hydration temperature. However, the compressive strength of hardened MPBC did not increase with higher calcination temperatures. In the 900-1 000 ~C temperature range, the hardened MPBC had a higher compressive strength. Imaging analysis suggested that the setting time and the highest hydration temperature of MPBC pastes were dependent on the size and crystal morphology of the B-MgO materials. The production and microstructure compactness of KMgPOa'6H2O, the main hydration product, determined the compressive strength.
文摘TiOz nanotubes (TiO2-NTs) were synthesized by the hydrothermal method. Co and Mo active components were supported on a series of the as-prepared TiO2-NTs samples which were calcined at different temperatures. The effects of support calcination temperature of CoMo/TiOz- NTs catalysts on their catalytic performance were investigated for selective hydrodesulfurization (HDS). The samples were characterized by means of the scanning electron microscopy (SEM), the transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy and H2 temperature-programmed reduction (Hz-TPR). The experimental results revealed that TiOz-NTs support calcined under 500℃ can maintain the nanotubular structure with higher surface area and pore volume. Meanwhile, the obtained supported CoMo/TiO2-NTs catalysts exhibited weak metal-support interaction, more octahedral Mo6+ species and high catalytic performance in selective HDS.
基金financially supported by the Distinguished Youth Funds of National Natural Science Foundation of China(No.51925402)the Ten Thousand Talent Program of China for Leading Scientists in Science,Technology and Innovation,the Shanxi Science and Technology Major Project Funds(No.20201102004)+3 种基金the Shanxi“1331 Project”Fundsthe Shanxi Province Key Laboratory Construction Project Fundsthe Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(Nos.2021SX-TD001 and 2021SX-TD002)the Shanxi Province Postgraduate Education Innovation Project(No.2021Y191).
文摘The effect of calcination temperature on the pozzolanic activity of maize straw stem ash(MSSA)was evaluated.The MSSA samples calcined at temperature values of 500,700,and 850℃ were dissolved in portlandite solution for 6 h,thereby obtaining residual samples.The MSSA and MSSA residual samples were analyzed using Fourier transform infrared spectroscopy,X-ray powder diffraction scanning electron microscopy,and X-ray photoelectron spectroscopy to determine vibration bonds,minerals,microstructures,and Si 2p transformation behavior.The conductivity,pH value,and loss of conductivity with dissolving time of the MSSA-portlandite mixed solution were also determined.The main oxide composition of MSSA was silica and potassium oxide.The dissolution of the Si^(4+) content of MSSA at 500℃ was higher than those of the other calcination temperatures.The conductivity and loss of conductivity of MSSA at 700℃ were higher than those of the other calcination temperatures at a particular dissolving time due to the higher KCl content in MSSA at 700℃.C-S-H was easily identified in MSSA samples using X-ray powder diffraction,and small cubic and nearly spherical particles of C-S-H were found in the MSSA residual samples.In conclusion,the optimum calcination temperature of MSSA having the best pozzolanic activity is 500℃,but excessive agglomeration must be prevented.
文摘LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)cathode material is prepared by sol-gel method and the effects of Nb^(5+)doping and different calcination temperatures on cathode materials were deeply investigated.Structural and morphological characterizations revealed that the optimal content of 1 mol%Nb^(5+)can stabilize layered structures,mitigate Ni^(2+)migration to Li layers,improve lithium diffusion capacity,and reduce lattice expansion/shrinkage while cycling.And calcination temperature at 800℃can not only ensure good morphology,but also suppress the mixed discharge of lithium and nickel in the internal structure.Electrochemical performance evaluation revealed that Nb^(5+)doping improves the discharge-specific capacity of the material,which is conducive to ameliorating its rate capability and cycle performance.And the material at 800℃exhibits the highest discharge specific capacity,the best magnification performance,low polarizability,and the best cycle reversibility.
基金Project supported by the National Natural Science Foundation of China(21377048,21307047)the Opening Project of Key Laboratory of Green Catalysis of Sichuan Institutes of High Education(LYJ1309)
文摘A series of CeO2-ZrO2-WO3 catalysts for the selective catalytic reduction (SCR) of NO with NH3 were prepared by hydrothermal method. The influence of calcination temperature on the catalytic activity, microstructure, surface acidity and redox behavior of CeO2-ZrO2-WO3 catalyst was investigated using various characterization methods. It was found that the CeO2-ZrO2-WO3 catalyst calcined at 600 ℃ showed the best catalytic performance and excellent N2 selectivity, and yielded more than 90% NO conversion in a wide temperature range of 250-500 ℃ with a space velocity (GHSV) of 60000 131. As the calcination temperature was increased from 400 to 600 ℃, the NO conversion obviously increased, but decreased at higher calcination temperature. The results implied that the higher surface area, the strongest synergistic interaction, the superior redox property and the highly dispersed or amorphous WO3 species contributed to the excellent SCR activity of the CeO2-ZrO2-WO3 catalyst calcined at 600℃.
基金supported by the National Natural Science Foundation of China(Nos.21906127,21677114,21876139 and 21922606)the Key R&D Program of Shaanxi Province(Nos.2019SF-244 and 2019ZDLSF05-05-02)+4 种基金the China PostdoctoralScience Foundation(No.2016M602831)Natural Science Foundation of Shaanxi Province,China(No.2019JQ-502)the Fundamental Research Funds for the Central Universities(Nos.xjj2017113 and xjj2017170)financial supports from the China Scholarship Councilthe support of K.C.Wong Education Foundation
文摘CuSO4/TiO2 catalysts with high catalytic activity and excellent resistant to SO2 and H2 O,were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH3.The performance of catalysts is largely affected by calcination temperature.Here,effects of calcination temperature on physicochemical property and catalytic activity of CuSO4/TiO2 catalysts were investigated in depth.Catalyst samples calcined at different temperatures were prepared first and then physicochemical properties of the catalyst were characterized by N2 adsorption-desorption,X-ray diffraction,thermogravimetric analysis,Raman spectra,Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,temperature-pro grammed desorption of NH3,temperature-programmed reduction of H2 and in situ diffuse reflectance infrared Fourier transform spectroscopy.Results revealed that high calcination temperature had three main effects on the catalyst.First,sintering and anatase transform into rutile with increase of calcination temperature,causing a decrement of specific surface area.Second,decomposition of CuSO4 under higher calcination temperature,resulting in disappears of Br(?)nsted acid sites(S-OH),which had an adverse effect on surface acidity.Third,CuO from the decomposition of CuSO4 changed surface reducibility of the catalyst and favored the process of NH3 oxidation to nitrogen oxides(NOx).Thus,catalytic activity of the catalyst calcined under high temperatures(≥600℃)decreased largely.
基金the National Natural Science Foundation of China(Nos.5150825451978319)+2 种基金Fundamental Research Funds for the Central Universities(No.lzujbky-2017-it98)College Students’Innovative Practice Training Program of Chinese Academy of Sciences(No.Y710171040)Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences。
文摘In this study,α-Bi2O_(3)/g-C_(3)N_(4) nanocomposite with direct Z-scheme was successfully prepared through calcination of BiOCOOH/g-C_(3)N_(4) precursor at different temperature.Meanwhile,the effect of calcination temperature on the physicochemical properties ofα-Bi2O_(3)/g-C_(3)N_(4) was studied.All results confirmed that calcination tempe rature greatly influences structural,morphology,surface states,photoelectrochemical property and photocatalytic(PC)perfo rmance ofα-Bi2O_(3)/g-C_(3)N_(4) composite.Furthermore,theα-Bi2O_(3)/gC_(3)N_(4) composite was applied as photocatalyst to degrade amido black 10 B dye under visible light irradiation.It was found that the composite synthesized at 400℃exhibited the highest PC performance due to the intense visible light absorbance and high separation efficiency of electron and hole pairs.Besides,the possible PC mechanism was proposed that the photo-generated charge carrier migration inα-Bi2O_(3)/g-C_(3)N_(4) photocatalyst followed a Z-scheme structure.Finally,the stability test also manifest that theα-Bi2O_(3)/g-C_(3)N_(4) composite photocatalyst has good stability and reusability,which was a promising candidate for wastewater treatment.
基金Supported by the National Natural Science Foundation of China(21543016)the Science and Technology Program of Shaanxi Province(2015 GY114)the Industrialization Cultivation Program of Shaanxi Province Education Department(15JF035)
文摘Activated carbon-supported bimetallic cerium-man- ganese (Ce-Mn/AC) materials were prepared by impregnation method to study the effect of calcination temperature on the structure and adsorption performance of absorbents. The obtained materials were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption-desorption iso- therm, Fourier transformed infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). As the results showed, the diffraction peaks of CeO2 decreased and even disappeared; Mn species were transformed from Mn3O4 to Mn2O3 on the surface of Ce-Mn/AC; the BET specific surface area increased first and then decreased on the elevating calcination temperature; the number of acid functions of AC was reduced after being modified by cerium and manganese All these changes were directly attributed to the synergistic effects between MnOx and CeO2. AC800 exhibited the best phenol adsorption capacity. The adsorption mechanism of phenol on Ce-Mn/AC was discussed with hydrophilic (hydrophobic) interaction and hard and soft acid-base theory.
基金supported by the National Natural Science Foundation of China(No.21077117)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB05050600)the Program of the Ministry of Science and Technology of China(No.2010AA064905)
文摘Carbon-modified titanium dioxide (TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation (PCO) of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400℃ had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range (〈 300℃). However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400℃ contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.
基金supported by the National Natural Science Foundation of China(No.21776051)the Research Fund Program of Key Laboratory of Fuel Cell Technology of Guangdong Province。
文摘Lithium-rich manganese-based oxides have the advantages of high discharge specific capacity, so they are potential candidates for advanced lithium battery cathode materials. However, they also have drawbacks to be solved such as serious irreversible loss of capacity and voltage decay in the cycling process. Surface coating method was used in this paper to modify the lithium-rich manganese-based oxide(LRMO,Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)) to improve its electrochemical properties. Zirconium-based compounds coated LRMO materials(ZBC@LRMO) were obtained via the reaction of lithium hydroxide with zirconium n-butanol and subsequent thermal treatment at different temperatures. The results of X-ray diffraction and transmission electron microscopy confirm that the crystal structure and composition of the ZBC coating layer vary with the calcination temperature. The coating layer obtained at 600 ℃ is composed of tetragonal ZrO_(2) and Li_(2)ZrO_(3). The ZBC@LRMO sample with tetragonal ZrO =2 and Li_(2)ZrO_(3) composite exhibits the best electrochemical performance: the discharge capacity of ZBC@LRMO can reach 296 mAh g^(-1) at 0.1 C and 120 mAh g^(-1) at high rate of 5 C.
文摘In this paper,the effect of high temperature calcination on the structure and properties of bauxite-based homogeneous clinkers calcined at different temperatures for different durations was studied.The results show that with the rising of calcination temperature and the prolonging of holding time,the volume density of bauxite-based homogeneous clinkers increases and the apparent porosity decreases.After high temperature calcination,the linear expansion of bauxitebased homogeneous clinker is smaller than that of the non-calcined ones.Whether calcined at high temperatures or not,the thermal shock resistance of bauxite-based homogeneous clinkers is good.The crystalline phases of bauxite-based homogeneous clinkers are mainly mullite and corundum.There is more glass phase in the bauxite-based homogeneous clinkers without calcination.After calcination at high temperatures the glass phase content decreases significantly,and the mullite crystals develop better forming the cross-network structure.
基金supported by the China Postdoctoral Science Foundation(2020M681503)Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2021-K56).
文摘As an industrial solid waste,pyrite cinder exhibited excellent reactivity and cycle stability in chemical looping combustion.Prior to the experiment,oxygen carriers often experienced a high temperature calcination process to stabilize the physico-chemical properties,which presented significant influence on the redox performance of oxygen carriers.However,the effect of calcination temperature on the cyclic reaction performance of pyrite cinder has not been studied in detail.In this work,the effect of calcination temperature on the redox activity and attrition characteristic of pyrite cinder were studied in a fluidizedbed reactor using CH_(4) as fuel.A series of pyrite cinder samples were prepared by controlling the calcination temperature.The redox activity and attrition rate of the obtained pyrite cinder samples were investigated deeply.The results showed that calcination temperature displayed significant impact on the redox performance of pyrite cinder.Considering CH_(4) conversion(80%–85%)and attrition resistance,the pyrite cinder calcined at 1050℃ presented excellent redox properties.In the whole experiment process,the CO_(2) selectivity of the pyrite cinder samples were not affected by the calcination temperature and were still close to 100%.The results can provide reference for optimizing the calcination temperature of pyrite cinder during chemical looping process.
文摘Precipitation was carried out to obtain manganese carbonate by adding a precipitating agent, sodium carbonate (NaCO<sub>3</sub>). This was followed by calcination of the manganese carbonate (MnCO<sub>3</sub>) to obtain manganese dioxide (MnO<sub>2</sub>). For precipitation tests, a pH ranging from 8 to 10, a time of one to two hours, and a temperature of 25°C and 50°C are the parameters that are considered. The calcination of MnCO<sub>3</sub> is carried out under the following conditions: time (1, 2, 3, and 4 hours) and temperature (370°C, 420°C, and 470°C). It should be noted that the temperature range selected for the calcination tests is based on thermodynamic data obtained using the HSC CHEMISTRY software. The results obtained show an effective recovery of manganese at 25°C, in one hour, with a pH of 8.5 with a precipitation yield and manganese content in the precipitate around 98.43% and 24.21%, respectively. During calcination tests, results show an increase in mass loss, for a constant calcination time, as temperature increases. On the other hand, increasing the calcination time at a given temperature causes an increase in mass loss. However, a significant decrease in mass loss is noted at 3 hours of calcination. The highest mass loss is obtained at a temperature of 470°C after 4 hours of calcination.
基金supported by the Natural Science Foundation of Fujian Province (No. T08J0129)the Science and Technology Developing Foundation of Fuzhou University (No. 2008-XQ-001)2007-year New Century Talents Supporting Program of Fujian Province (No.XSJRC2007-17)
文摘We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holding time on crystalline, microstructure and content of aluminum titanate materials to determine the preferred calcining temperature and holding time. XRD and SEM methods were utilized to characterize the crystalline and microstructure of each specimen, Rietveld Quantification software was used for the determination of different crystalline contents of specimens, and Philips plus software was applied to determine the cell parameters of aluminium titanate in different specimens. According to the experimental results, preferred calcining temperature is determined as 1400℃ and preferred holding time is 2 h, at which the grains of aluminum titanate grow completely and the purity of aluminum titanate is 97.2wt%.
文摘The swung gel fibers were hea, ted to 400 ℃ at 0. .5 ,1, 1.5,2,2.5,3and4 ℃ min^-1 of heating rate, respectivel, and soaked.for 1 h ; then heated to 600 ℃ at 3 ℃ min ^-1 of.heating rate amt soaked for 1 h at last calcined m 1 000, 1 100, 1 200, 1 300, and 1 400 ℃.for 1 h, respectively.
基金the financial support of the National Natural Science Foundation of China(Grant No.51872252)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant No.SJCX201356).
文摘Ternesite(4CaO·2SiO_(2)·CaSO_(4))-Ye’elimite(3CaO·3Al_(2)O_(3)·CaSO_(4))(simplified as TY)cement clinker was successfully prepared from steel slag at 1200℃in this study.XRD,TG/DSC and SEM were used to analyze the mineral composition and hydration products of the TY clinker.The sintering process and hydration mechanism of the TY clinker were investigated.Results show that a large amount of ternesite and ye’elimite have been formed at 1200℃,while ternesite has not been decomposed.Clinker minerals include ternesite,ye’elimite,gypsum and a small amount of iron phase.Iron phase from steel slag can promote the formation of liquid phase with the presence of gypsum at 1200℃and thus lead to the coexistence of ternesite and ye’elimite.The compressive strength of TY cement cured at 28 d is 59.5 MPa,which is higher than that of P.II 42.5 cement.This research provides a sustainable and energy-effective way for the reutilization of steel slag,an otherwise valueless waste.